This section introduces aspects that may facilitate a better understanding of the disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.
Mobile broadband continues to drive a demand for higher overall traffic capacity and a higher achievable end-user data rate in a radio access network. Several application scenarios in the future will require data rates up to 10 Gbps in local areas. The demand for very high system capacity and very high end-user date rates may be met by networks in which a distance between access nodes ranges from a few meters in indoor deployments up to roughly 50 m in outdoor deployments, i.e. with an infra-structure density considerably higher than the densest networks of today. The wide transmission bandwidth required for providing a data rate up to 10 Gbps and above may only be obtained from spectrum allocations in the millimeter-wave band. High-gain beamforming, typically realized with array antennas, may be used to mitigate the increased path loss at higher frequencies.
MMW networks have a number of properties that, generally speaking, make operations under the shared spectrum promising. Due to a small antenna size at higher frequencies, MMW networks heavily rely on the high-gain beamforming, which enables significantly higher resource reuse and alleviates interference between multiple networks. It is expected that these networks will predominantly be deployed in the form of “high-capacity coverage islands” in areas where a very high traffic demand is expected or a very high connection speed is required. This suggests that an area will normally be covered by one network only rather than having multiple parallel networks deployed by different operators that cover the same area. Hence, inter-network interference may predominantly occur between partially overlapping, adjacent or neighboring (i.e. with a certain distance in-between) networks. In such a situation, it is preferable to avoid fragmentation of the available bandwidth into one exclusive sub-band per network, since a large amount of spectrum would remain unused at times when networks are not simultaneously fully loaded, and peak data rates would be limited to a fraction of what could theoretically be achieved. It would instead be preferable that each MMW network may access the full available frequency bandwidth in order to maximize spectrum utilization and support peak data rates. In this case, inter-network interference may be unavoidable.
FIG. 1 illustrates a scenario of inter-network interference between two operating networks, e.g. two MMW networks, sharing a same spectrum, wherein a first operating network shown with a dotted pattern comprises three access nodes AN1-AN3 that serve user equipment UE1-UE3, respectively and a second operating network shown with a striped pattern also comprises three access nodes AN4-AN6 that serve UE4-UE6. The two operating networks are located in the same area and operate on the same spectrum. Hence they may cause interference to each other. The interference between links in different networks may be bidirectional or uni-directional. For example, link A1 between AN1 and UE1 in the first operating network may cause interference to link B1 between AN5 and UE5 in the second operating network, which is illustrated with a single head arrow; and link A2 between AN2 and UE2 in the first operating network may cause interference to link B2 between AN6 and UE6 in the second operating network and vice versa, which is illustrated with a double head arrow.
In this case, there is a need for a technology that may efficiently handle residual interference in border areas between two independent MMW networks. A solution of such kind of technology is interference coordination, which may coordinate scheduling of interfering links between different MMW networks so that interfering transmissions do not or at least less probably end up on the same radio resource.
FIG. 2 illustrates two different topologies for implementing resource coordination in the prior art, i.e. a centralized coordination topology and a distributed coordination topology.
In a centralized topology as illustrated in FIG. 2 (a), all information on resource usage of networks A, B and C may be collected by a central coordination function, which then makes a final decision on coordinated resource usage for multiple connected operating networks, e.g. MMW networks. In a distributed topology as illustrated in FIG. 2(b), two neighboring networks, e.g. networks A and B, may exchange information and negotiate with each other to determine the coordinated resource usage.
A patent application with No. PCT/CN2014/084640 has proposed a solution for coordinating resources in the distributed topology. The basic idea of this proposed solution is that only one network-wide blanking pattern is negotiated between involved operating networks for each of them as illustrated in FIG. 3. The blanking pattern divides the available radio resources into “blanking parts” as illustrated with white blocks in FIG. 3 and “usable parts” as illustrated with black blocks in FIG. 3. The coordinated blanking pattern may be applied in different levels, e.g. for the whole operating network (i.e. all links in the operating network are subject to blanking irrespective of whether they interfere or are interfered or not), for all links operated by a particular node in the operating network, some of which suffer from or cause interference, or for specific links operated by the particular node that suffer from or cause interference.
In this solution, either operating network involved in the negotiation is allocated a blanking pattern with a same blanking ratio for every round of coordination in order to main fairness between networks. As a result, each operating network has the same amount of resources available for scheduling, which is absolutely fair and thus may be easily accepted by both networks. This solution has offered several advantages like flexibility, timeliness, and absolute fairness in coordinating resources between operating networks.
There is also a need for a solution of coordinating resources in the centralized topology.